A body of air whose temperature and humidity characteristics remain relatively constant over a horizontal distance of hundreds to thousands of kilometers. Air masses develop their climatic characteris [..]

An extensive body of air having the same properties of temperature and moisture in a horizontal plane. 

A body of air covering a relatively wide area and exhibiting horizontally uniform properties.

A large expanse of air having similar temperature and humidity at any given height.

a large volume of air that is mostly consistent, horizontally, in temperature and humidity. Read more in the NG Education Encyclopedia

A widespread body of air, the properties of which can be identified as 1) having been established while that air was situated over a particular region of the earth's surface (airmass source regio [..]

An extensive body of air in a horizontal plane having fairly uniform properties of temperature and moisture.

large body of air with shared temperature and humidity characteristics associated with its area of origin e.g. maritime or continental; tropical or polar.

(n)- a large body of air in the troposphere that takes on the characteristics of pressure, moisture, temp. of that area

A mass of air with physical characteristics that distinguish it from other air.

A very large body of atmosphere defined by essentially similar horizontal air temperatures. Moisture conditions are also usually similar throughout the mass. Alluvia:

A large, more or less uniform body of air with nearly the same temperature and moisture conditions throughout

A large volume of air with certain meteorological or polluted characteristics, e,g, a heat inversion or smogginess-while in one location. The characteristics can change as the air mass moves away.

A large volume of air with certain meteorological or polluted characteristics--e.g., a heat inversion or smogginess--while in one location. The characteristics can change as the air mass moves away.

A large volume of air with certain meteorological or polluted characteristics--e.g., a heat inversion or smogginess--while in one location. The characteristics can change as the air mass moves away.

A large body of air with nearly uniform temperature and moisture content. There are six recognised airmasses that affect the British Isles denoted by their source region and then subsequent track. Pol [..]

Large body of air, often hundreds or thousands of miles across, containing air of a similar temperature and humidity. Sometimes the differences between air masses are hardly noticeable, but if collidi [..]

A large body of air that has nearly uniform conditions of temperature and humidity.

A huge volume of air, sometimes hundreds (or thousands!) of miles wide. An air mass has about the same temperature and water vapor everywhere inside the bubble. Sometimes they're warm and sometim [..]

a body of air

Impromptu religious service held on board an aircraft immediately following an announcement by the pilot that he is lost, having an engine problem, or running out of fuel.

In meteorology, an extensive body of air within which the conditions of temperature and moisture in a horizontal plane are essentially uniform.

Impromptu religious service held on board an aircraft immediately following an announcement by the pilot that he is lost, having an engine problem, or running out of fuel.

A body of air covering a relatively wide area and exhibiting horizontally uniform properties.

A large body of air throughout which the horizontal temperature and moisture characteristics are similar.

In meteorology, an air mass is a volume of air defined by its temperature and water vapour content. Air masses cover many hundreds or thousands of square miles, and adopt the characteristics of the su [..]

A large body of air that has similar horizontal temperature and moisture properties.

An extensive body of air throughout which the horizontal temperature and moisture characteristics are similar.

A huge volume of air covering thousands of square kilometers that is relatively uniform in temperature and water vapor concentration.

A large body of air

An extensive body of air throughout which the horizontal temperature and moisture characteristics are similar.

A large body of air having similar horizontal temperature and moisture characteristics.

An extensive body of air throughout which the horizontal temperature and moisture characteristics are similar.

An extensive body or large dome of air which has similar horizontal temperature and moisture characteristics. Often, a front separates two different air masses. Fronts are very narrow zones of transit [..]

An extensive body of air

A large body of air that's got basically the same temperature and humidity. When polar air masses slam into sub-tropical air masses we get fronts, which provide most of our winter rainfall.

A body of air covering a relatively wide area and exhibiting horizontally uniform properties.

An extensive body of air throughout which the horizontal temperature and moisture characteristics are similar.

 A body of air with uniform weather conditions, such as temperature, humidity and cloud type.

An extensive body of air throughout which the horizontal temperature and moisture characteristics are similar. AIR MASS THUNDERSTORM